Make Dockerfiles architecture neutral

[jmgrady]

This PRs included the following changes:

• Remove the -amd64 specification from the images used in the backend;
• Add a comment to the beginning of ./Dockerfile, ./Backend/Dockerfile, ./database/Dockerfile, and ./maintenance/Dockerfile to remind developers to not add architecture specific code to the Dockerfile; and
• Add a comment to the beginning of ./deploy/Dockerfile stating that it is only supported on Intel/AMD platforms.

---

This change is 

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.62%. Comparing base (87e875b) to head (0526e22).
Report is 27 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3310   +/-   ##
=======================================
  Coverage   74.62%   74.62%           
=======================================
  Files         279      279           
  Lines       10697    10697           
  Branches     1289     1289           
=======================================
  Hits         7983     7983           
  Misses       2351     2351           
  Partials      363      363           

Flag	Coverage Δ
backend	83.87% <ø> (ø)
frontend	66.53% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[imnasnainaec]

Reviewed 5 of 5 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @jmgrady)